Cro WatchesSeiko 6309-8900
Seiko 5 automatic (6309 family, export), about 1976-1990. What it is, how to date it, how to check it's original, and what it's worth.
The Seiko 6309-8900 is a Seiko 5 automatic (6309 family, export). It runs on Seiko's calibre 6309, an automatic movement with 17 or 21 jewels, beating 21,600 times an hour. It can't be wound with the crown and winds itself as you wear it, and the seconds hand keeps running while you set the time. Seiko made the 6309 from about 1976 to 1990. Seiko 5s in round, cushion and square cases with colourful sunburst dials. The 6309-7040 Turtle diver uses the same movement.
How old is it? The first digit of the serial number on the caseback is the last digit of the year, the second is the month (1–9, then O, N, D). On a 6309, made 1976–1990, a serial starting 15 means May 1981. Our Seiko Identifier works it out for you.
Is it original? The small dial code at 6 o'clock should start with 6309, like the caseback. If it starts with another number, the dial was made for a different model (a replacement dial). We have seen this reference with dial code 7009-6210 R1.
What is it worth? A running 6309-8900 in average condition usually sells for about €60–130 in Europe; an original dial, a strong colour and the original bracelet push it up. Price guide
Specifications
| Movement | Calibre 6309, automatic |
|---|---|
| Jewels | 17 or 21 |
| Beat rate | 21,600 per hour |
| Hand-winding | no |
| Hacking seconds | no |
| Power reserve | about 40-45 hours |
| Calendar | day-date |
| Made | about 1976–1990 |
| Typical EU value | €60–130 |
Have a 6309-8900? Check yours in seconds: open the Seiko Identifier with 6309-8900 filled in.
Questions
Can I wind a Seiko 6309-8900 by hand?
No. The 6309 winds itself as you wear it. To start it, move the watch gently from side to side for 20–30 seconds.
How do I set the day and date on a Seiko 6309-8900?
Most 6309 watches either change the day when you press the crown, or have a quickset when you pull the crown out one click. Never change the date between 9 pm and 1 am. Step by step: crowatches.com/seiko-set-day-date.html
How old is my Seiko 6309-8900?
Read the serial on the caseback: the first digit is the last digit of the year, the second the month. The 6309 was made about 1976–1990, which fixes the decade.